Methods of dissolving gas hydrates

Abstract

A method of dissolving a gas hydrate in a pipeline includes introducing a gas hydrate dissolving solution into the pipeline and allowing the gas hydrate dissolving solution to at least partially dissolve the gas hydrate in the pipeline. The gas hydrate dissolving solution includes a strong acid and a weak organic acid, and the strong acid expedites the reaction.

What is claimed is: 
     
       1. A method of dissolving a gas hydrate in a pipeline comprising:
 introducing a gas hydrate dissolving solution into the pipeline, the gas hydrate dissolving solution comprising sodium nitrite, ammonium chloride, a strong acid, and a weak organic acid; and 
 allowing the gas hydrate dissolving solution to at least partially dissolve the gas hydrate in the pipeline, where the strong acid expedites the reaction. 
 
     
     
       2. The method of  claim 1 , in which the strong acid comprises hydrochloric acid and the weak organic acid comprises acetic acid. 
     
     
       3. The method of  claim 2 , in which the hydrochloric acid is an aqueous solution comprising from 10 to 50 wt. % of concentrated hydrochloric acid and the acetic acid comprises glacial acetic acid with a concentration from 95 to 99.9 wt. %. 
     
     
       4. The method of  claim 1 , in which introducing the gas hydrate dissolving solution comprises introducing from 1 to 60 vol. % gas hydrate dissolving solution, based on a total volume of water in the pipeline. 
     
     
       5. The method of  claim 1 , in which the gas hydrate dissolving solution comprises:
 from 5 to 30 vol. % sodium nitrite solution, based on a total volume of water in the pipeline; 
 from 5 to 30 vol. % ammonium chloride solution, based on the total volume of water in the pipeline; 
 from 0.2 to 2 vol. % strong acid, based on the total volume of water in the pipeline; and 
 from 0.5 to 5 vol. % weak organic acid, based on the total volume of water in the pipeline. 
 
     
     
       6. The method of  claim 5 , in which the sodium nitrite solution comprises from 0.5 to 10 moles sodium nitrite. 
     
     
       7. The method of  claim 5 , in which the ammonium chloride solution comprises from 0.5 to 10 moles ammonium chloride. 
     
     
       8. The method of  claim 1 , in which the gas hydrate dissolving solution comprises:
 from 20 to 30 vol. % sodium nitrite, based on a total volume of water in the pipeline; 
 from 20 to 30 vol. % ammonium chloride, based on the total volume of water in the pipeline; 
 from 0.5 to 1 vol. % strong acid, based on the total volume of water in the pipeline; and 
 from 1 to 3 vol. % weak organic acid, based on the total volume of water in the pipeline. 
 
     
     
       9. The method of  claim 8 , in which the strong acid comprises from 10 to 20 wt. % hydrochloric acid and the weak organic acid comprises from 5 to 15 wt. % acetic acid. 
     
     
       10. The method of  claim 1 , in which allowing the gas hydrate dissolving solution to at least partially dissolve the gas hydrate takes less than 6 hours. 
     
     
       11. The method of  claim 1 , in which the gas hydrate dissolving solution comprises an aqueous solution comprising the sodium nitrite, ammonium chloride, strong acid, and weak organic acid. 
     
     
       12. The method of  claim 1 , further comprising inhibiting gas hydrate formation in the pipeline after introducing the gas hydrate dissolving solution. 
     
     
       13. The method of  claim 1 , in which a pressure of the pipeline is greater than 500 psi and a temperature of the pipeline is less than 100° F. 
     
     
       14. The method of  claim 1 , in which the gas hydrate comprises free water, carbon dioxide, hydrogen sulfide, methane, ethane, propane, n-butane, iso-butane or combinations thereof. 
     
     
       15. The method of  claim 1 , further comprising allowing hydrocarbon fluid to flow through the pipeline during introducing the gas hydrate dissolving solution, where the hydrocarbon fluid comprises methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, crude oil, carbon dioxide, hydrogen sulfide, dinitrogen, or combinations of these. 
     
     
       16. The method of  claim 1 , further comprising allowing the dissolved gas hydrate to discharge from the pipeline after allowing the gas hydrate dissolving solution to at least partially dissolve the gas hydrate in the pipeline. 
     
     
       17. The method of  claim 1 , in which introducing a gas hydrate dissolving solution into the pipeline comprises introducing the gas hydrate dissolving solution at an injection rate of from 0.5 gal/min to 20 gal/min. 
     
     
       18. The method of  claim 1 , in which the gas hydrate dissolving solution further comprises a corrosion inhibitor, a scale inhibitor, a demulsifier, or combinations thereof. 
     
     
       19. The method of  claim 1 , in which the gas hydrate dissolving solution further comprises glycol, a glycol ether, dimethylformamide, cesium formate, potassium formate, or combinations thereof. 
     
     
       20. The method of  claim 1 , further comprising heating the gas hydrate dissolving solution prior to introducing the gas hydrate dissolving solution into the pipeline. 
     
     
       21. The method of  claim 1 , in which the gas hydrate dissolving solution raises the temperature inside the pipeline after mixing to 20-120 deg C. 
     
     
       22. The method of  claim 1 , in which the gas hydrate dissolution solution further comprises gas hydrate inhibitors.